I know that I have hard water, and I cannot seem to get my wash routine right and was hoping for a little help as my poor DS has been getting what I think is ammonia rash (little red raised bumps and it goes away when he's in disposables).

Currently I do the following in a front loader HE machine:
cold pre rinse - no spin
Heavy Duty cycle - hot with extra rinse (i've tried rockin green & tide liquid - my next thought is tide powder)
I have been doing another quick wash with no detergent to make sure it all comes out, but i've heard this is not always a good idea with hard water? Is that true?

Any help would be appreciated as this is making my DH really not want to CD and it was hard to convince him in the first place.